textproduct: Rapid City

KEY MESSAGES

- Hot again today with elevated to near-critical fire weather conditions.

- Cooler conditions return middle of next week, with chances of rain.

- Confidence is increasing that the hot and dry weather returns next weekend.

UPDATE

Issued at 930 PM MDT Sun Jul 19 2026

Main update to the forecast was to extend the Heat Advisory again through most of Monday, but not for everyone.

The upper level high pressure that gave the area the hot weather will begin to shift southward tomorrow. This will allow the very hot weather to slide southward. So the Heat Advisory for the northern half of the CWA was allowed to expire this evening. Heat index values will still reach the upper 80s to 90s tomorrow but numbers like that are below the Heat Advisory threshold. The southern half of the CWA will still see hot temps in the 90s to near 100 with heat index values up to 100 degrees. Because of that, the Heat Advisory has been extended through most of Monday. Beyond that, temps are still expected to cool back to near or just below normal for late July.

One aspect that could bust this forecast is the potential for smoke to drift in from the north that would keep temps cooler than expected.

DISCUSSION

(This Evening Through Sunday) Issued at 118 PM MDT Sun Jul 19 2026

Upper air analysis continues to show a strong ridge sitting across much of the western CONUS, centered across CO/UT. Several waves have weakened and broadened out the northern edge of the ridge, resulting in more zonal flow over the the northern Plains. Surface obs show a surface low over Sask with cooler air pushing southward into NW MT/NE ND. Ahead of it...very hot temps continue across SE MT through the CWA but with an exception. A weak surface trough is extending across central portions of western SD into NE WY. KUDX radar shows light showers extending along the Cheyenne River valley to Rapid City to Newcastle. Just trace amounts are expected with these showers, but they are keeping temps cool, in the 80s. However, the temperature relief will be short-lived. Temps in the mid to upper 90s across NW SD are following the band of showers/clouds, which will increase temps over the Rapid City area later this afternoon. There is still uncertainty as to how the storm development will evolve later this afternoon. Instability will be moderate this afternoon. Linear shear will be best across NW SD, but overall the ingredients for organized severe wx will be better east of the CWA. With the dry boundary, wind will be the main threat with any storms that form, though some storms could briefly have hail. Convection will exit to the east this evening. Smoke from wildfires primarily across the Pacific NW is expected to move in from the north overnight and remain through Monday before perhaps exiting Monday night or Tuesday. Can't rule out early morning showers across the CWA Monday morning as the main front pushes through. Highs will again be warm on Monday, but think the near-100 degree heat should be limited to south of I-90. There is still some question as to whether a heat advisory extension may be needed for some of the western SD plains, but will let the evening shift reassess as the current advisory approaches expiration. Generally dry weather is expected through Tuesday, with much cooler temperatures in the 80s. Upper flow becomes more northwesterly, but models are hinting at a wave crossing the region through Tuesday night, which could bring another round of showers and thunderstorms thorugh Wednesday morning. As the ridge axis finally moves eastward toward the High Plains, an increase in monsoonal moisture is expected. GFS estimates PWATs of 150-175% of normal. With a series of strong, slow-moving waves crossing the region in the Wed/Thu timeframe...tapping into rich moisture, there is a possibility some portions of the northern Plains could see much more ample amounts of badly-needed rainfall. Temps will stay in the 80s...then models are suggesting a reestablishment of the ridge toward the end of the week, which could bring back hot temperatures.

AVIATION

(For the 12Z TAFS Through 12Z Tuesday Morning) Issued At 520 AM MDT Mon Jul 20 2026

VFR conditions will prevail today. Behind a cold front later today, expect surface smoke to move into the area. Right now, confidence is too low to add any VSBY restrictions.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM MDT /10 PM CDT/ this evening for SDZ026- 027-030>032-041>044-046-047-049-072>077. WY...Heat Advisory until 9 PM MDT this evening for WYZ055-058-059.